#[macro_use]
extern crate specs_derive;
#[macro_use]
extern crate specs_system_macro;

use ggez::GameError;
use specs::prelude::*;
use rand::Rng;

#[derive(PartialEq, Clone, Copy, Debug)]
pub enum TileType {
    Wall,
    Floor,
}

impl TileType {
    fn glyph(&self) -> carpet::CP437 {
        match self {
            TileType::Wall => carpet::CP437::from_char('#'),
            TileType::Floor => carpet::CP437::from_u8(0),
        }
    }
}

pub struct Map {
    tiles: carpet::Board<TileType>,
}

impl Map {
    fn new() -> Map {
        let mut rng = rand::thread_rng();
        let tiles = carpet::Board::new_from(80, 50, |x, y| {
            if x == 0 || x == 79 || y == 0 || y == 49 {
                TileType::Wall
            } else if rng.gen::<u8>() % 8 == 0 {
                TileType::Wall
            } else {
                TileType::Floor
            }
        });
        Map { tiles }
    }

    fn passable(&self, (x, y): (usize, usize)) -> bool {
        Some(&TileType::Floor) == self.tiles.get(x, y)
    }
}

#[derive(Component)]
pub struct Pos {
    x: usize,
    y: usize,
}

#[derive(Component)]
pub struct Renderable {
    glyph: carpet::CP437,
    color: carpet::Color,
}

#[derive(Component)]
pub struct Player;

impl Player {
    fn get_entity(world: &mut specs::World) -> Entity {
        let storage = (&world.read_component::<Player>(), &world.entities());
        storage.join().next().expect("No entities tagged as Player").1
    }
}

#[derive(Component)]
pub struct Motion {
    down: i8,
    right: i8,
}

impl Motion {
    fn move_player(world: &mut specs::World, down: i8, right: i8) {
        let player = Player::get_entity(world);
        world.write_component::<Motion>().insert(player, Motion { down, right }).unwrap();
    }
}

system_impl! {
    Draw(
        resource mut game_board: carpet::GameBoard<carpet::CP437>,
        resource map: Map,
        renderable: Renderable,
        pos: Pos,
    ) {
        game_board.clear();
        for (x, y, t) in map.tiles.iter() {
            game_board.set([x, y], t.glyph());
        }
        for (p, r) in (&pos, &renderable).join() {
            game_board.set_with_color([p.x, p.y], r.glyph, r.color);
        }
    }
}

system! {
    Move (
        resource map: Map,
        mut motion: Motion,
        mut pos: Pos,
    ) {
        let tgt_x = (pos.x as i8 + motion.right) as usize;
        let tgt_y = (pos.y as i8 + motion.down) as usize;
        if map.passable((tgt_x, tgt_y)) {
            pos.x = tgt_x;
            pos.y = tgt_y;
        }
    } finally {
        motion.clear();
    }
}

fn main() -> Result<(), GameError> {
    let mut game: carpet::Game<carpet::CP437> =
        carpet::GameBuilder::new()
        .name("game")
        .author("me")
        .resource_path({
            let base = std::env::var("CARGO_MANIFEST_DIR").unwrap();
            let mut path = std::path::PathBuf::from(base);
            path.pop();
            path.push("resources");
            path
        })
        .tileset("/haberdash.gif", [12, 12])
        .map_size(80, 50)
        .build()?;

    game.register::<Pos>();
    game.register::<Renderable>();
    game.register::<Motion>();
    game.register::<Player>();

    game.insert(Map::new());

    game.create_entity()
        .with(Pos { x: 40, y: 25 })
        .with(Player)
        .with(Renderable {
            glyph: carpet::CP437::from_char('A'),
            color: carpet::Color::Blue,
        })
        .build();

    game.on_key((carpet::VirtualKeyCode::W, carpet::KeyMods::NONE), |world| {
        Motion::move_player(world, -1, 0);
    });

    game.on_key((carpet::VirtualKeyCode::A, carpet::KeyMods::NONE), |world| {
        Motion::move_player(world, 0, -1);
    });

    game.on_key((carpet::VirtualKeyCode::S, carpet::KeyMods::NONE), |world| {
        Motion::move_player(world, 1, 0);
    });

    game.on_key((carpet::VirtualKeyCode::D, carpet::KeyMods::NONE), |world| {
        Motion::move_player(world, 0, 1);
    });

    game.run_with_systems(|world| {
        Draw.run_now(&world);
        Move.run_now(&world);
    })
}